This invention relates generally to electronic control systems and specifically to an electric motor control assembly including a single Hall effect sensor that senses a magnetic signal from a magnetized motor gear assembly, and that generates a control signal indicating the direction and/or speed of the electric motor.
Vehicle rear wiper assemblies have become a standard feature on many present-day motor vehicles. Typically, these rear window wiper assemblies include a wiper blade mounted upon a bracket which is coupled to a wiper arm. The wiper arm is attached to a wiper shaft rotatably driven in a cyclical oscillating manner by a helical gear. A reversible, fractional horsepower, dc electric motor serves to actuate the helical gear through an armature shaft-mounted worm gear enmeshed therewith. This type of rear window wiper arrangement is usually mounted upon a pivoting liftgate of a minivan, station wagon, sport-utility vehicle or the like.
Examples of conventional window wiper assemblies and motor mechanisms are disclosed with the following U.S. Patents:, U.S. Pat. No. 4,893,039 entitled "Windshield Wiper Motor" which issued to Isii on Jan. 9, 1990; U.S. Pat. No. 4,878,398 entitled "Driving Device for Window Wiper of Motor Vehicles" which issued to Heinrich on Nov. 7, 1989; U.S. Pat. No. 4,336,482 entitled "Rear Window Wiper Motor Control" which issued to Goertler et al. on Jun. 22, 1982; U.S. Pat. No. 4,259,624 entitled "Arrangement for Wiping a Vehicle Window" which issued to Seibicke on Mar. 31, 1981; U.S. Pat. No. 3,694,723 entitled "Motor Vehicle Windshield Wiper Having a Parking Position Outside the Wiper Area" which issued to Schneider et al. on Sept. 26, 1972; and, U.S. Pat. No. 3,665,772 entitled "Windshield Wiper Motor Link Depressed Park Mechanism" which issued to Beard et al. on May 30, 1972. All of these patents are incorporated by reference herewithin.
Some conventional vehicles also provide a rear window release lock or latch, actuated by a solenoid, which can be unlocked to allow for upward pivotal movement of the rear window in relation to the otherwise stationary liftgate. In combination therewith, a separate liftgate lock is often mounted upon the liftgate door for fastening the liftgate to the body to prevent inadvertent pivotal opening. This liftgate lock is traditionally operated by manual key or handle rotation, or through a separate electric motor or solenoid.
Additionally, separate motors and solenoids are required to actuate passenger door locks, antenna retraction mechanisms, headlamp cover retraction mechanisms, a fuel filler door lock and other similar functions. This increase in the number of electromagnetic devices has also resulted in the need for assembly controllers to control assembly component operation based on such factors as motor speed and/or direction.
One conventional approach to controlling small motor operation utilizes two Hall sensors each positioned at a position of 90 degrees relative to one another along the motor rotational axis in proximity to the motor. Each sensor senses the relative polarity of the motor and outputs a corresponding signal to the motor controller for motor control purposes. This approach, however, adds to overall system cost and assembly requirements, as two Hall elements are required and must be accurately positioned with respect to one another in proximity to the motor. Another approach uses motor monitoring systems that are contact sliding on the encoder disk or associated gears. These spring-loaded brush type contact systems, however, are often susceptible to component wear and signal contamination.